Multi-beam kinescope convergence circuits



July 8, -1958 v R. W. HAGMANN ETAL 2,842,708

MULTI-BEAM KINEscoPE coNvERGENcE CIRCUITS Filed Nov. 4, 1955 2 Sheets-Sheet 1 /A/vfwaks. Ji'abcrctllflf 1mm July 8, 1958 R. w. HAGMANN ET Al. 2,842,708v

MULTI-BEAM KINEscoPE coNvERGENcE CIRCUITS Filed Nov. 4, 1955 2 sheets-suene h I .MW. m

, lection circuitry. -Y j l One type of cathode ray tube, or-fkinescope, with which i V`A voltagel pulse at the frequency of theA other.e1ectron 7 MULTI-BEAM-KINEscoPE,coNvERGENcE .fCmcUITs Y lbeam 'deflecting wave'obtained from a secondary winding Y f-the outputtransformer for the other dellectionwave is applied to al plurality of series circuits, each comprising anladjustable inductance element, a compensating capaci- .Robert Wayne Hagmann, Lancaster, andfJohngiClarence 5 tor elementf and a Vresistanceelementof low. impedance ',Coope'r, 1Lititz,-Pa., assignors to Radio Corporation of 1Amenca,acorporation ofiDelaware Y ApplicaamNvember 4,.19ss,seria1N'0. 545,9s6f sclaims. (el. sis-1a);

v I The invention relates tosysternsV for controlling. thedeflection of electron beamsof, cathode ray tubes, and it particularly pertains to such-systemsin which arp1urality of electron beams are deected by Acommon dethe invention may be successfully used isa colorkinethree-gunwshadow-maskcolor Akinescopej by H. D.. Law

published in the Proceedingsof the IRE volume a9, No1 20- Pedance ofthe shunt Circuits- Y l0, for October 1951 at'page'1l8r6. The target electrode: ,structure of such a tube comprises in-parta luminescent .gscreenin which different.- phosphor areas produce dif. Vferentlygcolored light whenexcitedzby yelectron 1beamssim `determines the vparticular color ofthe light produced.

lForsatisfactory operation of Vsuch ,kin'escopesf it isI necesysary to effect-substantial convergence of the .dinerent-elec.- r tron beams at all points on the rasterJformedf-by.:de

with 'respect Vto lthat 4of theinductance element. 'Sawtooth voltages are thus produced at' the other. deilection rate and the amplitudes thereof may beladjusted byvarying Ythe inductances in the series circuits. The'cOnVerging IOQWindings are shunted across the series connectedcompensatingV capacitor and resistance element. 'Upon .in-

tegration by application ot' the` sawtooth voltagestithe highly inductive convergingl windings variabl'eamplitude current waves .of parabolic vwaveform are produced. "The 15 compensating capacitance element provides amore ,suitable Waveform for Vconvergence and also reduces Y Vthe power loss by permitting the use 'of larger values of resist-V ance elements. The" 'resulting parabolic current j'waveY j formj is phase corrected by effectively varyingthe' im- 'adjustablel differential .in-ductance element and another adjustableinductance element common to thfebeam conpirnging from Herent angles; Theanglerofmpingemem 25 Averging wmdmgs associated with two of the electron beams;l Adjustment y'ofthe differential element `apporf tions" the inductanrce in each 'beam'converging winding fleeting the three electronV beams in two n'lutu'allyiper-` 30 'for Proper convefge at au Points of the Tastel' A v.p,eridicu1ar directions. lA generaldiscussionofthisbeamr v, 'l convergence problemwill be foundfin an articlezentitled,

' KifDeiiectionv` and convergence in color'lkinescopes 'TYLAv VW. Friend, published in thelroceedingsl of .the.fI;RE, .Volume.39, No; 10, for October 1951 at Page1249. One Vtype of multi-beam kinescope to which the-invention par-ff.

ticularly-pertains includes a-pair of magnetic polefpiecesV Y located internally of the kinesope envelope for teach beam. These internally located pole pieces areenergizedy These magneticcomponents may be entirelyT i An object of the inventionv is to provide improvedjvcir- Accordingv to the invention-parabolic convergence cur-V Y l 'rent Waves for applicationto the pole-piece exciting Windf, ings of a multi-rbeamkinescope areobtained byrintegra ytion of pulse and sawtoothvoltage waves in resistive vand *'inductive'reactance circuits. The circuit -features adjustableresistance elements interposedin series with thel'e'ads.-`Y`

ofone electronbeam deilecting winding whichfinjconfv j junction with the inductance component ofthe associated beam converging winding provides variable amplitude .parabolic current waves iowing through each yofrthe highly inductive beam converging windings. "Other/.resis-f `v tive elements connected across a'centre-tappedjislated :winding on the output transformer. for Athe one deflection l wave provides variable' amplitude positivel'o'r negative '1fsawtooth.voltagejwaves atlthesame'deflection'rateffor 70 Y v i l`@tilting theparabolic waves@ .ff "prgessedjjin aY sound 1;-F,amplifyingcircuit;ian Aaural fdiflerentalresistance element andanother'resistancelele- 'ement' are connectedin common to `the two beam con- :verging-windings .to shift'the phase in similar mannerjf i, Further according to the inventionythe trajectory of 35'ia-Vthrdelectron beam,.which may have serious "f-drooping with respect'to those of' theother electron beams,.is brought intoconvergence by shunting -theseries :resist- `ance felement .byV ani adjustable in'ductance. component providingl 'an improved dynamic current; waveform i and f by magnetic components arranged outside'the kinescope mfp-efmtngthe Useof'adl'ustabie ildltors Ofavsngl? Ringek f j envelope. .p Yelectromagnetic or theymay include some permanent f `magnetic structure since vthe internally'located'pole pieces 4,usually require vstatic asf'well asgdynamic energization.V .In fgeneraLit isdesirablek to provide ysuch'convergenceV "'rneans for kinescopes `with the minimum of additional?` .components arranged for maximum ease of adjustment.

df'values in'the series4 circuits. Y j

"fb'eJfully appreciated,` an express embodimengjgivenfby way of example only, is' described hereinafter" with refa erence to theaccompanying drawing-in whichz Y Fig. l is afunctional diagram of a'televisionreceivingY l, apparatusA in which the inventionl may 'beincorporated;Av

' QFig. 2'is .a crossfsection view of a.multibeam1l inescope joffthe type towhichithe usevofl the inventionv is particuembodimentofthe invention.

Y Udiagram of portions of a color televisionfreceiver:tdgwhich fthe'. invention is 'particularly adaptable, and wh1ch- .re i( "iceivenfmay otherwise comprise l entirely conventional circuitry. .In 'such a' receiver, color televisionsignalsappear- -ing'jat'an antenna are appliedjtoz'aradio.frequency .wave

amplifying-circuit andthe output `therefro1n isapplied along' with the wave obtained from a localbeat escillation Y "generating circuit to a frequency chiangingcircuit.'j'flhe i' v :'putput' 'ofjthe frequency changingjhcircuitjisjapplied to* an (intermediate freauehsy '.(I--F-)L amnlsr which .mvfbef i' 'one having separatei channels for picture Y andrsoundzsigi A nals oirone'vhaving a: single channel infwhichbothipicture,

'Y .and soundsignals are amplified at`theV same time. Thenals 16"' to a` video-.detnodulating `circuit 17 l forjderiving va video vfreqnency- (Vi-'Filwavefromthe televisionf-sig'- signal discriminating 4ci`rcuit,fan audioy,trequencyl (AL-F.)

larly applicable; and Fig. 3is a schematic diagramjnoif" an cuits. tributing network may be coupled to the synchronizing component colors when excited by electrons.

amplifying circuit for reproduction by a transducer, usually in the form of a loud speaker. The output of the V.F. amplifying circuit is applied to a translating circuit 19 for converting luminance and chrominance components into proper form for application to the signal input circuitry of an image reproducing device 2() incorporating a tri-color kinescope. The output of the video frequency amplifying circuit is also applied to a synchronizing pulse separating circuit 24 to separate the synchronizing pulses from the picture signals and to separate the horizontal synchronizing pulses from the vertical. The separated vertical synchronizing pulses are applied to a vertical deflection Wave generating circuit 25 and thence to a vertical dellection wave amplifying circuit 26, while the horizontal synchronizing pulses are applied-to a horizontal deflection frequency oscillator and frequency control circuit 27 and thence to a horizontal deflection wave amplifying circuit 28. A high voltage and focus voltage generating circuit is coupled to the horizontal deilection wave amplifying circuit to develop focus and ultor potentials for the kinescope. The vertical deflection wave amplifying circuit 26, the horizontal deilection wave Vamplifying circuit 28, are coupled to the image reproducing device 20 to supply vertical and horizontal deflection waves for deflecting the electron beams of the kinescope. The vertical deection wave amplifying circuit 26 and the horizontal dellection wave amplifying circuit 28 are connected to a convergence wave generating circuit 30 which may include circuitry according to the invention, for converging the individual beams of the multi-gun kinescope. A low voltage power supply, normally connected to the local A.-C. power lines, is arranged to furnish direct energizing potentials to all cir- An automatic gain control amplifying and dis pulse separating circuit 24 or the video frequency demodulating circuit 17 or to the video amplifying circuit 18 to supply control potentials to the desired ones of the circuits previously mentioned. Normally, the R.F. and I.F. amplifying circuits are at least so supplied.

The kinescope of the image reproducing device 20 may be of the same general type as that disclosed in the H. B. Law paper hereinbefore mentioned.` The kinescope preferably has a luminescent screen provided with a multiplicity of small phosphor areas arranged in groups and capable of producing light of the dilerent In.back of and spaced from the screen there isV an apertured masking electrode having an aperture for and in sub-' stantial alignment with each group of phosphor areas. The luminescent screen and the masking electrode may have planar or partially sperical surfaces; the invention being equally applicable to either form of target electrode structure.

The kinescope also has a plurality of electron beams equal in number to the number of component colors in which the image is to be reproduced. Conventionally, three electron guns, which may be entirely conventional in structure consisting of a cathode, a control electrode and a focusing electrode, are arranged substantially parallel to produce three separate electron beams by which to energize respectively blue, red and green phosphor areas of the screen of the kinescope. The kinescope also contains a beam accelerating electrode, or ultor, consisting of at least one cylindrical grid electrode and a conductive wall coating on the. inner surface of the envelope of the kinescope and extending out to the region ofthe target electrode structure. When these electron beams are properly converged at the target structure, the electrons pass through the apertures of the masking electrode from diterentdirections and impinge on different phosphor areas of each of the groups so as to produce light in the three component colors. The electrodes of the kinescope may be energized in the conventional manner and the color information signals are apexclusion of the others.

plied so that the electron beams are modulated in intensity in accordance with the information carried by the color-representative video signals derived from the translator circuit 19. The video signal source will not be described further herein since it does not form in and of it- .self an essential part of the invention.

Associated with the color kinescope is a deflection system yoke, which may be entirely conventional and, in which may be mounted two pairs of suitably placed windings electrically connected so that, when properly energized, electromagnetic fields are produced to effect angular deilections of the electron beams in both the horizontal and vertical directions to scan the usual rectangular raster at the target electrode structure. Deflection waves for application to the electron beam deilecting windings are obtained from the vertical and horizontal deflection wave amplifying circuits 26 and 28 respectively.

The beam Vconvergence system also includes a plurality of electromagnetic field producing elements arranged about the neck of the kinescope adjacent to the predellection paths of the electron beams. An example of such construction is shown in Fig. 2 wherein three magnet assemblies SIR, 31G and 31B arranged about the neck of a kinescope envelope 35. The precise location of the magnet assemblies is not necessarily indicated in Fig. 2 but it is to be understood that each of the magnet assemblies is located relative to the path of one of the electron beams to influence that one beam to the virtual The magnetic elds produced by these magnet assemblies are transverse to the associated beam paths and in a direction to move the associated beams radially relative to the longitudinal axis of the trode structure.

kinescope. The convergence magnet assemblies SIR- 31B are usually energized by a substantially unidirectional current component to effect an initial convergence of the electron beams substantially at the target electrode structure. Normally, convergence is initially made at the center of the screen; however, this initial convergence may be made at any point, for example at one corner ofthe raster. In order to do this, the unidirectional energizing current component is effected in such a way that the magnet may be individually energized in different magnitudes.

The convergence magnet assemblies SIR-31B are also dynamically energized by wave energy derived from suitable generating means so as to effect a variation in the magnitude of the transverse elds produced and to vary the deflection of the individual electron beams as a function of the overall deflection of the three beams. In this way suitable variations are made in the `convergence angles between the various beam components in the individual beams so as to produce the desired convergence of the beams substantially .at all points of the target elec- All of the magnet assemblies being the same, only one will be described in detail. Hereinafter the sulllxes R, G and B are added to the reference numerals in reference to the, components for the Red, Green and Blue exciting electron beams respectively, but the suilix will be dropped where the discussion of the general case is made more clear by so doing. The magnet assembly 31B comprises a core, which may be in one piece, but is shown in two pieces 36B, 37B having legs 38B, 39B extending at right angles to the main body of the core. lf direct current .is utilized to afford static convergence, the core might conveniently be in one piece. AsV shown, however, the core of the magnet assembly 31B is *splitV into two pieces 36B, 37B and mounted between the core pieces, in suitable recesses formed therein, is a substantially cylindrical permanent magnet 40B. This magnet is polarized substantially diamctrically so -as to present north and south poles in the two halves thereof substantially as indicated. `The permanent magnet 40B may be provided with suitable adjusting facilities,

1a'lternatively the windings l maybe Wou'ndas av unitaryv structure and mounted!` on theA main body portion fof the core.- ,Ajset of-pole' piecesdSB, :44B is provided inter- ;nall'y of the Yneclcof the kinescope envelope nS'S'ffor each "ofthe convergence magnet assemblies? `AThefinte'rnal lpole pieces 43B, l64B Vare varranged to'increase the eliectiveness of the associated magnet assemblies by decreas* ingthe reluctance ofthemagnetic circuit-and considerl'ably improving the iiux distributienet the field pro.

' ducedbetween the pole pieces.' The convergence magnet ,assemblies SIR-31B produce vfields which in the vicinity Y ofthe electroni beams associated therewith arefsubstan-Y vtially transverse to the axis ofthe kinescope.l The elec- ,tronv beam associatedV with each ofv themagnet assemblies may'be readily moved toward or away from the `longitudinal tuber axis by adjustingthe amount of magnet-'ic' flux in the respective assemblies- 31. The .direction and magnitudev of such mcw'emerntV is controlledifby .the

VIVA"ener'g.ization of the ,windings 41, 42 fand` rotation off-the vpczrrnanent magnet 40. v v flThe Yconvergence'magnet assemblies 131 may be energizedf byrme'ans of the circuit arrangement shown kin. Fig.

i3'. -The convergence magnet assemblies maybe substantially identical, and may be renergized- Vby substantially f identical circuits. Therefore, thek description will be limited tothe particular'circuits by Whichthe windings 3 /41'and 42 of the convergence .magnet'assemblyglilA are energized, it being understood that'the same` description y,applies equallyy as well to the circuits Yillustratedrfor energizing thevother convergence magnet windingsexcept I 'l wheref specifically noted.

- Q'Referring, to Fig. 3, a synchronrzingg'sawtooth voltage @wave of verticaloeection frequency at input terminals `Srl-,52 is applied by Way of connections includingra co1 Y ,pling capacitorSS to a verticalrdeilection wayeamplifying A Vtube'59l vVertical sawtoothmcurrent waves. are inducedv inVVV y' VVV"afvertical deflection wave outputv transformer i611* b y ha primary winding 61 connected -in vthe anode circuitofthe Vvertical amplifier tube 59. The sawtoothdellectionwave Y vappearingN across a secondary windingv62` is appliedY by 1meansincludingblocking ,capacitors 6.3-65 .to a vertical deflection system1 winding .comprising sections "66, 67. i y ,No provisions'are shown in the circuitylorl deflection centering of the `scanning beams, but 'conventional'.icenter r`rying:y current circuitry maybe. employed ,in knownrnanner. A.sawtooth voltage wave, athorizontal'.'deflection'y Vrate isl applied at input terminalsl', 72 of the horizontal -amplifying tube 74; rAvsawtooth'current-wave is induced Y 1 by. the connectionstotheiamplifying tube 7,4m avi/inding l76 of the horizontal vdellecti'on wave output t'rfansformer 78.` 'The' deflectionpulse voltage and sawtooth Ycurrent [wave appearingin'the output portion ofmthef '@Winding y76 is' applied to Va horizontal deflection system winding 'eofriprising two Asections"til', n8Z"th'e"`l`atter fof 'fwhich isshunted byv an anti-ringingcapacitorf f 'nog centering provisions have been shown, ybut these may i ,be readily suppliedaccordinggtothe, known art. Y

In the example shown in. F1g. 3, two 'jdiierentconi ligurations of circuitry`Y according *tothe* ',invention? are showinV One exampleis shown in connectioniwithihe i verticalk Vdeection."'systemjandthe other in connection Withk the `horizontal deflection system, but its-hoiildjbe Iunderstood Vthat either may be` used in both:systemsV or interchanged, if desired. Furthermore, the 'converg. ling windings 41 are shown lasconnected only in the ver-1` tical systemand the-windings 42as'conne'ctedonly,inthe horizontal system.' y' It j'should be understoodiv that; those windings "41, 42 may be lconnectedgin `series `or parallel YandY 'ther r separate convergence .currentsapplied tof both '...wi1'1dir1gs.A In such kcase it is necessary uto isolatenone A y source from 'the other but this is within the skill ofertho'se i i 6 r vfamiliar with the art. 'Anexamplefof su'ch'isolating connection isA 'given infthe copeiiding 9U."JS.1Z` Patent applica- "A parabolic currertI wave isV produced in'the vVertical beam converging windings 41 byi integrationrof-sawtooth vertical'V deflection Waves-'applied thereto;V .The sawtooth vs'fav'esi are` developed across-- a4 plurality fof' variablyr tapped resistancef elements or potentiometers. 9.11, con'nectedfin lOparallel' and interposed inseriesV ywith Vthe verticalY beam deilectingwinding sections-66, 67.- vThere 4isonefelement for leachV circuit 'desiredY f In the example shown, there is a potentiometer-91kvforthe:red controllingvelectron lbeam,"anothefr'potentiometer91G fornthe green controlling electron beam, 'anda further potentiometer for therblue `controllingeletcron beam. Movementrof i the arms 92 of :the potentiorneter's191i` serves ytofadjust the amplitude'sfof Athe sawtooth Yvoltage components Aavailable, for: thel parabolic `current.'Waves for developing the sawtooth.' currentwaves; Hence the, amplitudeiofV con- 'verging the individualelectron beams inthe vertical diyrectio'n is'likevviseLvaried. l y

' f `Bymeans of'` othervariablyftapped resistanoe `elements Y 1 .orf potentiometer'sf. 94K, 94G l andA 94B :connected imparg Va1le1i..across 'afcententappedz secondary `winding V93y of i the verticalirdeectiongwave;.output'transformer 60,. posi- *nativelylthe p otentiometers94fmay becenter tapped` and Q interconnected; to 'establish:appoint-V of reference potenop tial, but this entails vmoreex'pense than the center tapped .,winding93. Moving thepotentiometer `arm to either sideI of., neutral causes .either a positive or negativel pulse wavetoappearbetween the arm and the point of reference potential of amplitudeproportionalto the degree Arof'movement of the arm. The plurality'of yconvergence pole-piece exciting windings 41 are `individuallyjconnected between the arms 92 of the parabola amplitude controlling potentiometers 91 and.` the arms 95 of` they tilt controlling otentiometers 94t v' Agcolor, .Purity 'magnet is used with tri-colorfrkinescopes Aof the typementioned ghereinbefore; This? magnet Y operates by;directingthethree electron beams across the longitudinalaxis offthe'kinescope. This beam movement, :togetherwith tube geometry and somefcomponent tol;

Yby ,positioning the-arms v95 on the sawtooth Waveamplitude :settingupotentiometers 94. Fonthisfr'eason `these -potentiometers 94 are usually termed "tiltgcontrols.V In the example shown in Fig. 3, parabolic current ,flection Wave'transformer f78-." Qle terminal ofthisfhori- -v zontalgwindingis maintainedfatapoint ofreference poten- Y o tial,shownas; ground, tofvvhichthegconverging windingsv Y l142`'a1 returned. -Thepotheriterminal oitheconverging :winding1102;iisficonnectedftoy series circuits. comprising Van adjustable ihdueta'nce feleinen 104,;fa. compensating n capacitive elementV 105 and a resistance element-196 yhavingan impedance' low with-respect to that of" theinductvr ance-'element 104g@ The converging windings 42 'are con- "neeted in :shunt to Vthose portions Vof the 'series'f circuit i i y "ngcapacitor'105V vandfthe resistf i ''.anceelernent(105;v se esfc'ircuit is predominately 1inc n' A Y i i i Y sdavvto `lt-hiK4 'li'voltageacoss theresistanceelernentrlt;` cornpen-"-j erances, makes tiltingfnecessary, 'Ifhe'parabolic-'waves are .tilted 4,or shiftedsonthat-,the minimum amplitudepoints *Y v`are either 'toward the/.beginning or. the end ofthe waves,

sative capacitance element 105 deforms the sawtooth wave to render it slightly S-shaped and symmetrical to provide a more perfect parabolic current waveform in the converging windings 42. In addition larger values of resistance elements 106 may be used, resulting in lower power loss and less loading on the high voltage rectifier.

With the adjustable inductor 107B removed from the circuit, adjustment of the blue controlling electron beam integrating inductance element 104B varies the amplitude of the sawtooth current waveform flowing in the blue converging winding 42B. The phase of the parabolic sawtooth wave is controlled, or tilted, by varying the value of resistance of the resistance element 106B, which alters the RC constant of the series circuit portion comprising the capacitance element 105B and the resistance element 106B. Variation of this resistance element 106B changes the integration, resulting in a change in phase of the parabolic current waveform in the converging winding 42B. Such an arrangement as described may be used for all three of the converging windings 42R-42B.

One type of tri-color kinescope has the three color controlling electron beam generating guns so oriented within the envelope of the kinescope 35 and so energized in accordance with the present Federal Communications Commission Standards for color television broadcasting wherein the blue color controlling electron beam is subject to an effect known as drooping The other two electron beam forming guns are arranged 'substantially side by side with the kinescope 35 in position for operation, and energized in accordance with the regulations whereby drooping is not a problem and whereby closely similar operating characteristics are obtained from the other two electron guns. The drooping and similar characteristics are eliminated according to the invention by shunting the resistance element 106B by an inductance element 107B. The inductance element 107B may be adjustable to phase or tilt the parabolic current waveform so that the resistance element 106B need n'ot be adjustable, but an adjustable resistance element 106B and a fixed inductor may be used, or both may be adjustable as desired. The addition of the inductance brought about by the inclusion of the inductor 107B improves the integrating action in such manner as to eliminate the drooping characteristic. This arrangement may be used for all three of the converging windings 42 if the integrating action is insruiiicient for use with the particular type of tri-color kinescope tube under consideration.

As shown in Fig. 3 the adjustment of therconvergence circuits for the red and -green color controlling electron beams is rendered easier and quicker by dividing the inductance element 104 and the resistance element 106 into three portions so that adjustment of the, total inductance and the total resistance in each of the convergence circuits controls the amplitude and tilt of the parabolic current waveforms for the two circuits' simultaneously. Portions of the inductance element 104 and the resistance element 106 are arranged for differential adjustment so that the two electronV beams are made to operate in the same desired manner without requiring further adjustment of the totalwinductance" and total resist- Vance in the two convergencecircuits.4 The adjustable element 106R-G of a tilt balancing potentiometer is coupled to both the red and green convergence circuits by means of compensating capacitors 105K and 105G. The arm of the balancing potentiometer 106R-G is connected to-one terminal of a variable resistance element 106RG, lthe other terminal of which is connected to the point of fixed reference potential, shown as ground. Thus, varying the adjustable resistance element 106RG will vary the total resistance in the two convergence circuits and determine the tilt, while adjustment of the differential resistance element 106R-G serves only to apportion the resistance between the two convergence circuits.

V/ith tri-colored kinescopes of the type described, the electron guns are mechanically tilted toward the central axis of the kinescope so that the individual beams virtually converge at the center of the phosphor screen. However, because of manufacturing tolerances, a static component of magnetic eld is necessary to set the beam direction of each gun precisely. This field is obtained by means of the rotatable permanent magnets 40 in the convergence coil assemblies 31 as shown in Fig. 2. rThe field required is a function of the error and the square root of the ultor potential, the latter of which follows the power line voltage in shunt tube high voltage regulating systems. Both the vertical and the horizontal dynamic convergence waves are applied to the converging windings 41, 42 for alternating current flow only. When the components of magnetic field these voltages produce are added to the static component required for center convergence as previously adjusted, the total eld when scanning the center of the raster will be in error by an amount equal to the instantaneous value of the dynamic convergence voltage. This error may be corrected by adding a compensating iield of equal value and opposite sign by means of resistance elements 108 which are connected to a source of intermediate potential obtained from the same low voltage rectifier that supplies the circuits developing the dynamic components; that is, the horizontal and vertical deflection wave translating stages whose outputs vary directly with the power line voltage. In the circuit as shown in Fig. 3 the compensating eld varies in the same manner as the dynamic elds so that for normal power line voltage variations, there is high degree of tracking over the raster, resulting in excellent beam convergence. The centering currents may be applied only to the vertical converging windings as shown, only to the horizontal converging windings, or they may be applied to both, as in the case of interconnected converging windings.

Those skilled in the art will determine the values of components to be used in various applications of the invention from the teachings herein, however, the values Vof pertinent components listed below which were used in a successfully operated color television receiver having convergence systems as shown in Fig. 3, are given as a guide in the practice of the invention.

Ref. No. Component Type or Value Tri-color kinescope Convergence system winding...

21AXP22.

1,200 turns on 0.5 mh.

Winding on V3 ierrite cores.

Vertical amplifier tube GBL? (parallel).

Horizontal amplier tube GCDG.

Cathode resistor Vertical linearity control- Vertical parabola control. 0-100 ohms.

Vertical tilt winding d; 10 v.toground. Vertical tilt control 0-100 ohms.

Series resistor (Blue only) ohms.

Horizontal pulse wave source... v.toground. Horizontal integrating inductors. 0.2-1.2 Inh. (differentiel inductors 104R and 104C with slug in center 0.9 mh.)

Compensatmg capacitors 0 5 mid.

Series resistors 0-30 ohms. Series resistor.. 40 ohms. Common resistor. 0-40 ohms. Dierential resistor- 2O ohms. Dropping resistors. 82 kilohms.

The power supply delivered approximately/V400 volts between the points marked land ground.

The invention claimed is: l. A beam convergence circuit arrangement for a multibeam kinescope, the electron beams of which are ydeflected in two directions normal with respect to each other, including a plurality of electron beam converging windings through which currents of substantially parabolic waveform of frequency correspondingto electron beam detlection in one of said directions are desired, a

' Y plurality of series circuits each comprising an inductance element, a capacitance element, and a resistance element connected in series, means to apply a voltage pulse train of recurrence ratecorresponding to said deflection in said one direction across said series circuits,rmear1s to couple said beam converging windings individually across at least said resistance elements of said series circuits, and an inductance element shunted across at least one of said resistance elements, a plurality of other electron beam converging windingsrthrough which currents of' substantially parabolic waveform of frequency corresponding to electron beam dellection in the other of said directions are desired, a plurality of adjustably tapped resistance elements connected in parallel and having the adjustable taps individually connected'to given Yterminals of said other electron beam converging windings, another electron beamdelecting winding connected in common to given terminals of said resistance elements, means to apply deilection waves of frequency corresponding toV ,felectron beam deection in said other direction between ythe other terminals of said resistance elements and the l other terminal of said other beam deflectinglwinding, a number of adjustably tapped resistanceV elements connected in parallel and having adjustable taps individually f connected lto the other terminals of said other beamV cont verging windings, a winding connected to the terminalsV of the last said parallel connected resistance elements for applying a voltage pulse thereto of recurrence rate corresponding to electron beam deilection in said other direc-k tion, and a connection between an intermediate point of said-interconnected windings and parallel connected resistance elements and the other yterminals of the rst said parallel connected resistance elements.

2. A beam convergence circuit arrangement for a 1 multibeam kinescope, the electron beams of which `are def flected in two directions normal with respect to each other,

including a plurality'of electron beam converging windings through which currents of substantially parabolic waveform of frequency corresponding to electron beam deflection in one of said directions are desired, a plurality of series circuits each comprising an inductance element, a capacitance element, and a resistance element connected in series, means to apply a voltage ,pulse ltrain of recur rence rate corresponding to said deilection in said one di- .rection across said series circuits, means to couple said beam converging windings individually across at least said Y resistance elements, and an inductance kelement shunted across at least one of said resist-ance elements, at least one Y of said shunt connected elements being adjustable.

3. A beam convergence circuit arrangement for a ,multi'beam kinescope, the electron beams of which are 'deflected in two directions normal with respect to each other, including a plurality of electron beam convergingV windings through which currents of substantially Vparabolic waveform of frequency corresponding tov electron ybeam deflection in one Vofisaidv directions are desired, a plurality of adjus'tably tapped'resistance elements connected in parallel and having the adjustable taps individually connected to given terminals kof Vsaid electron beam -converging windings, anlelectron beam deflecting winding connected in common to given terminals of said resistance of the last said parallel connected resistance elementsfor Y applying a voltage pulse theretoof recurrence rate cor responding to electron 'beam dellection in said'one Ydire-cf tion, and a connection between an intermediate point of said interconnected Vwindings and parallel connected resistance elements and `the other terminals of the first said 'Y Y parallel connected resistance elements.

4. A beam convergence Ycircuit arrangement for a multibcam kinescope,fthe electron beams of which are dellected in two directions normal with respect Yto each other, including a plurality of electron' beamY converging windings through which currents of ksubstantially para- 'bolic waveform of frequency correspondingV toelectron beam deilectionin one ofsaid directions arerdesired, a

plurality of series circuits each comprising inductance` element and a resistance element common to all of saidr series circuits, a lplurality o-f series circuits each comprising ,Y

a differential inductance element, a capacitance' element and a differential resistance element,V means coupling said series circuits in parallely between given terminals of said common inductance element and said'common resistance element, means to apply a Vvoltage pulse trainof recur- Vrence rate corresponding tcsaid deflection in said one di-V rection between the other terminals of said common inductance element and said common resistance element, means to c-ou-ple said electro-n Ibeam converging windings y Y individually between the other terminal of said common resistance element and the junctions between said differ# ential inductance elements and said capacitance elements.

5. A beam convergence circuit arrangement for an internalV convergence pole-piece type multi-beam itine-Y scope electron beams of which are deflected'in two directoins normal with respect to each other by common electron beam `deflectng fields, including a plurality of electron beam converging windings through which currents of substantially parabolic waveform of frequency corre-Y spending to electron` beam dellection in one of said directions are desired, an inductance element having two differential terminals Vandra common terminal arrangedV to present the same total inductance betweenY each of the diiferential terminals andthe common terminalwth in-V ductance varying differentially between thetwo diierential terminalsyan adjustable resistance element having dilferential terminals and a common terminal andjarranged to present the same total Iresistance betweensaid diierential terminals while varying the resistance between e said differential terminals and said common terminal, ca-

pacitance elements interconnecting individually the differ-y ential terminals of said inductance'elemen't and said resistance element, means to apply'a voltage pulse train of recurrence rate corresponding to said detlection infs'aid Y' one direction between said common terminals of said; inductance `and said resistance elements, andmeans `to con-* nect said electron beam converging windings individually between the junctions of said capacitance and inductance elements and said common terminalV of said resistance elet ment. Y

References Cited in the le of this patent UNITED STATES PATENTS I 2,707,248 2,742,589 Goodrich 'Apr."1 7, 1956 Goodrich Apr. 26, '19557r Giuffrida Apr. 24,1956` f 

